Insulating dielectric media



Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE INSULATING DIELECTRIC MEDIA many No Drawing. Application February 5, 1934, Serial No. 709,902. In Germany February 18', 1933 Claims.

The present invention relates to new insulating dielectric media, more particularly it relates to insulating dielectric media containing or consisting of chlorinated aromatic hydrocarbons 5 containing the cyanogen group.

In accordance with the present invention it has been found that chlorinated aromatic hydrocarbons containing the cyanogen group display many advantages as insulating dielectric media. They exhibit also advantages over the chlorinated aromatic hydrocarbons of viscous or wax-like nature, such as polychlorinated naphthalenes, diphenyls, etc. which are also used as insulating dielectric media.

The new insulating dielectric media have a pronounced insulating effect and a high dielectric constant which makes them especially suitable for use in condensers.

For the purpose of the present invention espe- 20 cially homogenous plastic and solid products come into consideration but other products can also be used when yielding homogenous mixtures with other viscous, oily, waxor resin-like insulating dielectric media as, for instance, trans- 25 former oil, castor oil, wax-like chlorinated naphthalenes, parafiin, colophony, bitumina and asphalts. In many cases it has proved advantageous to use mixtures of the different isomeres and homologues.

The new dielectric media can be prepared in various Ways, for instance, by transforming NH2,SO3H or halogen containing compounds into the respective cyanogen containing compounds. They can also be prepared by chlorin- 35 ating aromatic hydrocarbons containing the cyanogen group. By distilling the crude product obtained by chlorination in most cases mixtures are obtained which can directly be used as insulating dielectric media. Thus, for instance, by chlorinating a-naphtho-nitril with or Without chlorination catalysts products of a chlorine content of 30 to 35% can be obtained, the dielectric constant of which is about twice as high as that of the products containing no cyanogen group. A chlorinated a-naphtho-nitril prepared in this manner and having a chlorine content of about 35% has a dielectric constant of about 10 while chlorinated naphthalenes with the same chlorine content or such a chlorine content that also the cyanogen group is replaced by the respective amount of chlorine shows dielectric constants of below 5.

1. The use of a chlorinated naphtho-nitril as a dielectric and insulating medium in the preparation of insulating materials and condensers.

2. The use of a mixture of chlorinated naphtho-nitrils as a dielectric and insulating medium in the preparation of insulating materials and condensers.

3. The use of a chlorinated a-naphtho-nitril as a dielectric and insulating medium in the preparation of insulating materials and condensers.

4. The use of a mixture of chlorinated a-naphtho-nitrils as a dielectric and insulating medium in the preparation of insulating materials and condensers.

5. The use of a mixture of chlorinated a-naphtho-nitrils having an average chlorine content of about 30 to 35% as a dielectric and insulatingmedium in the preparation of insulating materials and condensers.

- WILHELM LOMMEL.

RUDOLF ENGELHARDT. 

